Lawn mower sharpening machine



March 11, 1 F. E. DENNEWITZ LAWN MOWER SHARPENING MACHINE 2 SHEETSSHEET1 Filed May 5, 1950 k Q FEED E4 \DEN JF (C INVENTOR NE W/ 72,

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March 11, 1952 F. E. DENNEWITZ 2,588,492

LAWN MOWER SHARPENING MACHINE Filed May 5, 1950 2 SHEETS-SHEET 2 I 54 49INVENTOR.

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Patented Mar. 11, 1952 UNETED STATES PATENT OFFICE 2 Claims.

This invention relates to lawn mower sharpening -machines, and moreparticularly to a machine utilizing a motor-driven grinding wheel forsharpening both the reel blades and cutter bars of lawn mowers.

It is among the objects of the invention to provide an improved machinefor sharpening lawn mowers, which machine supports the lawn mower reeland associated mechanism with the reel in anaccurately adjusted positionand supports a motor-driven grinding wheel for straight line movementslongitudinally of the blades of the lawn mower reel to accurately grindthe cutting edges of such blades, which includes guides for the grindingwheel to accurately determine the angle and depth of cut made by thegrinding wheel on the cutting edges of the blades, which also supports alawn mower cutter bar in proper position for grinding by the samegrinding wheel used to grind the reel blades, which will quickly andaccurately grind the reel blades and cutter bar of a lawn mower, andwhich is simple and durable in construction, positive and accurate inoperation, and easy to use.

Other objects and advantages will become apparent from a considerationof the following description and the appended claims in conjunction withthe accompanying drawings, wherein:

Figure 1 is a front elevational view of a lawn mower sharpening machineillustrative of the invention; Figure 2 is a cross-sectional view .onthe line 22 of Figure 1;

Figure 3 is a front elevational view of the upper portion of the machinewith a lawn mower reel mounted in operative position in the machine;

Figure 4 is a cross-sectional view on the line 4-5 of Figure 3;

held 3111 spaced apart and substantially parallel relationship to eachother by suitable transverse :srame members, as indicated at [5, l6, l1and I8 jn Fiigures l and-2,and-;are reinforced by diagonal braces, asindicated at I9 and 20,

substantially parallel to the rack 3|.

End members 2| and 22, which may also be conveniently formed of angleiron, are disposed at the top of theframe, the end member 21 connectingthe upper end'of the two posts H and I3 and the end member 22 connectingthe upper ends of the two posts I2 and M. A tubular rail 23 extendslongitudinally of the frame at the upper end of the latter and isrigidly secured at its opposite ends to the end members 2| and 22intermediate the length'of such end members. A secondary end member 24extends between the posts H and [3 below and substantially parallel tothe top end member 2| and a secondary end member 25 extends between theposts 12 and i4 below'and substantially parallel to the top end member22. A bracket 26, in the form of a heavy metal strap, is secured to theend member 2! and extends upwardly therefrom at a location between therail 23 and the front side of the frame, and a similar bracket 2! issecured to and extends upwardly from the top end member 22 at acorresponding location. A second or upper rail 23 extends at its endsthrough apertures provided in the brackets 26 and 21 and is rigidlysecured to these brackets by pairs of clamp nuts 29 threaded onto thescrew-threaded end portions of the second rail.

The second rail 28 is disposed somewhat above and forwardly of the rail23 and the two rails are substantially parallel to each other.

Two notched racks 30 and 3| are secured to the inner sides of the postsII and 13 below and substantially parallel to thesecondary end member24, the rack 30 being disposed below and I v Two similar racks 32 and 33are secured to the inner sides of the posts 12 and I4 below andsubstantially parallel to the secondary end member 25 with the rack 32disposed below and substantially parallel to the rack '33,

frame and is supported at its opposite ends in notches of the two lowerracks 30 and 32, this rod being adjustably movable between the rear andfront sides of the machine by selection of the notches in which the endsof the rod are supported. Asecond :rod 35 is supported at its oppositeends in the notches of the upper racks a! and 33, the position of thisrod transversely of the frame being also adjustable by selection of thenotches in the upper racks in which the ends of the rod are supported.

A motor carriage 31 is mounted on the rail 23 for movementlongitudinally of this rail. This carriage comprises a top plate 38disposed substantially parallel to the plane of the top of the frame andtwo channel members 39 and 48 disposed below the plate 39 with their webportions mutually opposed and in spaced apart, substantially parallelrelationship to each other. The upper flanges of the channel members 39and 48 are secured to the under side of the plate 38 and the lowerflanges are positioned adjacent the rail 23. Two sets of rollers withthree rollers in each set are positioned one set at each end of thecarriage for supporting the carriage on the rail 23. The three rollersin each set include a center roller 4| disposed between the web portionsof the channel members 39 and 46 and rotatable about a substantiallyhorizontal axis. The two upper rollers of the two sets rest on the topof the rail 23 and support the weight of the motor and the motorcarriage. Each set of rollers also includes two rollers 42 and 43rotatable about substantially vertical axes and bearing against the rail23 at'respectively opposite sides of the latter for guiding the motorcarriage along the rail.

An electric motor 44 is mounted on the upper surface of the plate 38 ofthe carriage and a belt pulley 45 is secured on one end of the motorshaft.

A U-shaped grinding wheel carriage 46 is mounted on the rail 28 formovement longitudinally of this rail. Two rollers 41 and 48 arejournaled in this carriage near the closed end or bight thereof and reston the top of the rail 28 and the two legs of this U-shaped carriage depend downwardly from the rail 28. The leg portions of the carriage 46are provided with registering, rectangular openings and two fiat bars 46and 49 are secured, each at one end, to the channel member 39 of themotor carriage and extend through the openings in the grinding wheelcarriage 46, in spaced apart and substantially parallel relationship toeach other, to the side of the grinding wheel carriage 46 remote fromthe motor carriage.

At the side of the grinding wheel carriage 46 remote from the motorcarriage, the two arms 48' and 49 are provided with registering tappedholes and set screws or bearing screws 58 and are threaded through thetapped holes in the bars 43 and 49, respectively, and have pointed innerends. An externally screw-threaded grinding wheel axle 52 is provided inits ends with conical depressions in which the pointed inner ends of thebearing screws 50 and 5| engage to rotatably support this axle betweenthe bars 46' and 49.

A disc-shaped grinding wheel 53 has a central aperture receiving theaxle 52 and a belt pulley 54 is threaded onto the axle at one side ofthe grinding wheel. A clamp nut 54 is threaded onto the axle at theopposite side of the grinding wheel to clamp the wheel against thepulley and rigidly secure the wheel to axle 52 for rotation with thepulley. A V-belt 55 extends through the openings in the legs of thecarriage 46 and drivingly connects the motor-carried belt pulley 45 tothe wheel-carried belt pulley 54.

registering apertures in the bars at the corresponding ends thereof anda spacer sleeve surrounding the bolt between the tWo bars. The bars arealso secured in spaced apart relationship by a bolt 51 which extendsthrough registering apertures in the bars between the two legs of thecarriage and a spacer sleeve 58 surrounding the bolt 5'! between thebars. Nuts 59 threaded onto the bolt clamp the bars against the oppositeends of the spacer sleeve and the bolt extends outwardly of both of thebars 48 and 49. Tension springs 66 and 6| are secured at their lowerends to the respectively opposite ends of the bolt 51 and at their upperends to the carriage 46 by suitable pins 62 and tend to resiliently liftthe bars 48 and 49 and the grinding wheel 53.

One of the legs of the carriage 46 is provided at its lower end withprojections 63 and 64 extending inwardly of the rectangular opening inthis leg of the carriage, which projections engage the bottom edges ofthe bars 48 and 49, respectively, and limit downward movement of thesebars and the grinding wheel.

The bars 48' and 49 interconnect the motor carriage 3'! and the grindingwheel carriage 46 so that the two carriages move together longitudinallyof the rails 23 and 28.

Flexible strands, such as the chains 65 and 65', are connected, each atone end, to the carriage 46 at respectively opposite sides of the latterand extend in opposite direction away from the carriage 46 toward theends of the frame. The chain 65 is carried over a sheave 67 supported onthe end member 2| of the frame and depends at the outer side of this endof the frame. A weight 68 is connected to the depending end of the chain65. The chain 66 is carried over a sheave 69 carried by the end member22 of the frame and depends at the corresponding side of the frame, anda weight 19 i secured to the depending end of this chain. The twoweights 68 and 79 facilitate the movement of the motor carriage andgrinding wheel carriage with the' motor and grinding wheellongitudinally of the rails 23 and 28.

Adjustable stops H and 12 are mounted on the rail 28 to limit the rangeof movement of the carriage 46 longitudinally of this rail.

A fixture for supporting a lawn mower reel and the associated lawn mowermechanism n the rods 35 and 36 is provided, and comprises two internallyscrew-threaded, tubular sleeves 13 and 14. The sleeve 13 has abifurcated arm 15 extending perpendicularly therefrom, and disposed atits outer ends below the rail 35. This arm is secured to the rail 35 bytwo U-bolts 16. The sleeve 14 has a bifurcated arm 11 extendingperpendicularly therefrom and secured to the rail 35 by two U-bolts 16'.An arm 18 extends perpendicularly from the top end of the sleeve 13 inthe direction opposite the arm 15 and is provided at its end remote fromthe sleeve with an eye receiving the rod 36. The sleeve 14 is similarlyprovided with an arm 19 which extends perpendicularly from the upper endof the sleeve 14 in a direction opposite the arm 11 and is provided atits end remote from the sleeve with an eye which also receives the rod36. A screw shaft 80 is threaded through the sleeve 13 and provided onits upper end with a head 8| having a V-shaped notch therein and a screwshaft 82 is threaded through the sleeve 14 and provided on its upper endwith a notched head 83. An arm 84 extends upwardly from the arm 18 nearthe rod 36 anda similar arm-85 extends upwardly l f;ItQm--the arm 19also adjacent the r d 1 5,-. A

'-;lever -86 is pivotally connected at one end 170 the upper vend ofthearm "84 and is provided-in its opposite end with 'a V-shaped notchwhich is opposed to the notch-in the screw shaft head 8I. Alever 81ispivotally secured at one end to the upper end of the arm 85 and isprovided-near its opposite end with a notch which opposes thenotchin'the 'screw'shaft head 83. Clamp screws Wand-89 extend throughthe levers 89 and '81, respectively, and are threadedly engaged with thearms I8 and I9 to force the notched ends of the levers 86 and 81 towardthe screw shaft heads 8| and 83.

With this arrangement, the cross rod 99 of a lawn mower assembly may beclamped on the heads BI and 83 of the screw shafts by the levers 86 and81 to position the reel blades of the lawn mower adjacent the grindingWheel 53.

A U-shaped lever 9I is pivotally mounted at one end on the rod 35between the sleeves I3 and I4 and carries a bolt or pin 92 which isadjustable longitudinally of this lever. When the lever is swung up tothe position illustrated in Figure 3, the bolt 92 is engaged under theroller 93 of the lawn mower assembly to hold the lawn mower reel 94 inproper position for grinding of the reel blades, as is particularlyillustrated in Figure 4.

A guide or gauge 95 is carried by the bar 48' at the outer side of thegrinding wheel 53 in position to rest upon a lawn mower blade beingground and to move the blade rotationally so that it follows thegrinding wheel in the movements of the latter longitudinally of theframe and to also limit the depth of the out made by the grinding wheelon the cutting edge of the blade. This guide or gauge is'adjustablerelative to the bars for varying the depth of cut to be made.

The various components of the grinding machine can be adjusted so thatthe machine will accommodate substantially any size and style of lawnmower reel.

When it is desired to grind the cutter bar of a lawn mower, a fixture isused, as particularly illustrated in Figures 1 and 2.

This fixture comprises an elongated rod 96 clamped on the heads 8| and83 by the levers 86 and 81 and two flat links 91 and 98 secured each atone end to the rod 96 at spaced apart locations on the latter. A secondrod or shaft 99 is secured to the links 9'! and 98 at the ends thereofremote from the rod 96 and is substantially parallel to the rod or shaft96. Hooks I99 and I9I are hooked over the rail 28 near the respectivelyopposite ends of this rail and extend through sleeves, as indicated atI91, mounted on shaft 99 and are adjustably connected to the shaft 99near the correspondingly opposite ends of this shaft by hand knobs I92and I93 threaded onto the screw-threaded end portions of the hooks I99and I9I respectively at the ends of sleeves I9'I remote from shaft 28.

The links 91 and 98 are provided intermediate their length with tappedholes, and set screws I94 and I95 are threaded through these holes andare engageable at their inner ends with the ends of a lawn mower cutterbar 99 positioned between the links 9'1 and 99, to hold the cutter barin position for sharpening by the grinding wheel 53, as clearlyillustrated in Figures 1 and 2.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to =beconsidered in all respects :asillustrative and :not restrictive, "the scope of the invention beingindicated by the pp claims rather han by he f in description, and allchanges which come within the "meaning and range'of equivalency of theclaims are, therefore, intended to be embraced therein.

I claim:

'1. A lawn mower sharpening machine comprising a rectangular framehaving atop end, two rails extending across said frame in spaced apartand substantially parallel relationship to each other, one of said railsbeing disposed at the top end of said frame and connected at its endsthereto and the other of said rails being disposed above the top end ofsaid frame, brackets secured to said frame at the upper end thereof andextending upwardly therefrom supporting said other rail, a firstcarriage mounted on said one rail for movement longitudinally thereof, asecond carriage mounted on said other rail for movement longitudinallythereof, said second carriage having an opening therethrough, a pair ofarms, secured to said first carriage and projecting through the openingin said second carriage, means resiliently supporting said arms fromsaid second carriage, a grinding wheel disposed between said arms andjournaled thereon at the side of said second carriage remote from saidfirst carriage, a motor mounted on said first carriage, means drivinglyconnecting said motor to said grinding wheel, and a fixture adjustablymounted on said frame for supporting lawn mower blades in position to beground by said grinding wheel.

2. A lawn mower sharpening machine comprising a rectangular frame havinga top end, two rails extending across said frame in spaced apart andsubstantially parallel relationship to each other, one of said railsbeing disposed at the top end of said frame and connected at its endsthereto and the other of said rails being disposed above the top end ofsaid frame, brackets secured to and extending upwardly from the upperend of said frame supporting said other rail, a first carriage mountedon said one rail for movement longitudinally thereof, a second carriagemounted on said other rail for movement longitudinally thereof, saidsecond carriage having an opening therethrough, a pair of arms securedto said first carriage and projecting through the opening in said secondcarriage, a grinding wheel disposed between said arms and journaledthereon at the side of said second carriage remote from said firstcarriage, a motor mounted on said first carriage, means drivinglyconnecting said motor to said grinding wheel, and a fixture adjustablymounted on said frame for supporting lawn mower blades in position to beground by said grinding wheel, said second carriage comprising aU-shaped body receiving said other rail and having spaced apart andsubstantially parallel legs depending at respectively opposite sides ofsaid other rail, two rollers journaled in said body at the closed endthereof and bearing on the top of said other rail, springs in said bodyconnected between said body and said arms suspending said arms from saidbody, and stop means on said body limiting downward movement of saidarms relative to said second carriage.

FRED E. DENNEWITZ.

(References on following page) REFERENCES CITED The following referencesare of record in. the file of this patent:

UNITED STATES PATENTS Number Number 8 Name Date Warner July 12, 1910Klay Sept. 6, 1921 Anderson Mar. 14, 1922 Root Nov. 22, 1932 CarpenterJan. 3, 1939 Ingleman Mar. 7, 1939 Utterback Jan. 16, 1940 Smith Apr.28, 1942 Machovec Apr. 12, 1949 Comstock Jan. 3, 1950

